   [cofx browser url]
   (let [history-index (:history-index browser)
         history       (:history browser)]
-    (let [new-history (conj (subvec history 0 (inc history-index)) url)
-          new-index   (dec (count new-history))]
-      (update-browser cofx
-                      (assoc browser
-                             :history new-history
-                             :history-index new-index)))))
+    (when history
+      (let [new-history (conj (subvec history 0 (inc history-index)) url)
+            new-index   (dec (count new-history))]
+        (update-browser cofx
+                        (assoc browser
+                               :history new-history
+                               :history-index new-index))))))
 
 (defmulti storage-gateway :namespace)
 

(fx/defn update-browser-name
  [cofx title]
  (let [browser (get-current-browser (:db cofx))]
    (when (and (not (:dapp? browser)) title (not (string/blank? title)))
      (update-browser cofx (assoc browser :name title)))))

(fx/defn navigation-state-changed

  {:events [:browser.ui/open-empty-tab]}
  [cofx]
  (debounce/clear :browser/navigation-state-changed)
  (navigation/navigate-to-cofx cofx :empty-tab nil))
